Extremely arid conditions, coupled with mega-storms and other bad weather, have many Americans thinking that something must be done to help the environment. / LM Otero, AP

by Wendy Koch, USA TODAY

by Wendy Koch, USA TODAY

Americans are increasingly convinced that the planet's climate is changing and show more support for regulating greenhouse gas emissions, finds a Duke University online survey released Thursday.

The share of Americans who say climate change is occurring - 50% say definitely and 34% say probably - has rebounded, reaching what may be its highest level in national polls since 2007, according to the survey of 1,089 adults conducted Jan. 16-22. Slightly more than half, or 54%, say climate change is primarily the result of human activity such as the burning of fossil fuels.

"Whether in response to extreme weather events like mega-storm Sandy or the improved economy, public opinion has clearly rebounded from its low point of a couple years ago," says co-author Frederick Mayer, an associate professor at Duke's Sanford School of Public Policy.

More people also want to see action to fix the problem, echoing President Obama's pledge to tackle climate change in his second inaugural address last month. Nearly two-thirds, or 64%, strongly or somewhat favor regulating greenhouse gas emissions from power plants, factories and cars, and requiring utilities to generate more power from "clean" low-carbon sources such as solar or wind energy.

Yet relatively few respondents favor market-based approaches such as a tax on carbon. Less than a third, or 29%, favor cap-and-trade, in which companies buy pollution credits if their emissions exceed a limit. Although support is low, many Americans have yet to form an opinion about this approach; 36% say they're neither for nor against it.

Like other surveys on climate change, the Duke poll finds strong partisan differences in the perceived seriousness of the problem. About half of Democrats say it is "very serious" while 35% of independents and 17% of Republicans agree. Funding for the poll, which has a margin of error of 3 percentage points, came from Duke's Climate Policy Working Group.